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摘要
In this paper, the data from temporary seismic stations in the North-South seismic zone set up under the project ChinaArray Phase I (2011-01-2014-06) and the project ChinaArray Phase II (2013-02-2015-12) are analyzed with the Systematic Analysis Method of shear-wave splitting (SAM method) to study the crustal anisotropy of the North-South seismic zone. The environment of regional stress and the tectonic characteristics revealed by shear-wave splitting parameters are discussed as well as the relationships between regional principal compressive stress directions and fracture distributions. The results show that the fast shear-wave polarization directions are consistent with the regional principal compressive stress directions, which gradually varied from NE to NNW from north to south. The NE and WNW or NW faults also have a great influence on the directions of principal compressive stress. The polarization directions of fast shear-waves at stations near the strike-slip faults are parallel to the fault strikes, and a part of these shear-wave polarization directions are nearly perpendicular to the fault strikes, which are similar with the regional principal compressive stress directions. Several stations exhibit complex features, reflecting the complexity of tectonic environment in the study area. The delay times of slow shear-waves in the south part are higher than the north part, reflecting that the southern section has a greater degree of anisotropy in crust and the tectonic deformation is more intense. Compared with the upper mantle anisotropy of the North-South seismic zone, it is inferred that there may exist a complicated crust-mantle coupling phenomenon inside of the Sichuan-Yunnan rhombic block. The shear-wave splitting in the crust can not only reflect the regional stress characteristics, but also can reveal the regional tectonic information.
- 出版日期2017-6
- 单位中国地震局地震预测研究所
